1. Field of the Invention
This invention relates to nonwoven materials comprising time release additives, which nonwoven materials are used in the production of personal care absorbent articles such as diapers, training pants, incontinence garments, and feminine care products such as sanitary pads and panty liners, health care products including surgical gowns and drapes, surgical wraps, wound dressings, fenestration reinforcement materials, industrial wipes, work wear and the like. The time release additives may be added to the polymeric materials used in the manufacture of the nonwoven materials or they may be added as a surface treatment to the nonwoven materials. The time release additives may be used to impart a feature that is deficient in the polymeric material, or they may be used to impart a feature to the nonwoven materials upon being activated or triggered by an event such as an insult.
2. General Background
The use of cage molecules as a means for controlling the release of a desired property over an extended period of time is well-known in the art. Cage molecules are molecules that contain cavities or interstitial spaces which may be used to entrap materials for a wide variety of applications. Such cage molecules which have been used include zeolites and cyclodextrin.
U.S. Pat. No. 5,603,974 teaches a barrier film composition comprising a thermoplastic web comprising a thermoplastic polymer and dispersed cyclodextrin composition having substituents that compatibilize the cyclodextrin in the film. The thermoplastic/cyclodextrin film obtains substantial barrier properties from the interaction between the substituted cyclodextrin in the film material with a permeant. In this case, the permeant is complexed or entrapped by the cyclodextrin compound and held within the film, thereby preventing the permeant from passing through the film into the interior of a film, an enclosure or container.
U.S. Pat. No. 5,844,033 teaches a polycarbonate resin composition comprising substantially a polycarbonate resin and zeolite having tannic adsorbed thereon, wherein the molecular weight reduction (that is, quality deterioration) of the polycarbonate resin caused by its decomposition is suppressed by the inclusion of zeolite (having adsorbability and slow releasability) having tannic acid (a polyhydric phenol compound) adsorbed thereon.
U.S. Pat. No. 5,384,186 teaches solid consumer products (compositions) containing solid cyclodextrin inclusion complexes of actives, which are typically hydrophobic materials like perfumes, flavoring materials, pharmaceutical actives, antibacterials, bleaches and the like, which products/compositions are either in particulate form, compounded with other materials in solid form, such as tablets, pellets, agglomerates and gel sticks, or attached to a substrate.
U.S. Pat. No. 4,722,815 teaches a synthetic resin product containing various substances selected from among perfumes, insectifuges, rust preventive, mildewproofing and bactericide which are inactivated by forming an inclusion compound thereof in cyclodextrin and coating them with glycitols to thereby prolong the duration period of the substance.
U.S. Pat. No. 3,341,488 teaches the release of materials such as active chemicals contained in the inner adsorption region of crystalline zeolitic molecular sieves in a reaction zone where they may, for example, serve as curing agents for rubber formulations, epoxy resins or as catalysts for the formation of polyurethane foams.
See also, French patent publication 2,665,169 which teaches cyclodextrin containing compounds containing phenolic antioxidants for heat stabilizing polymers such as polypropylene and Japanese Patent Abstract JP-108922 which teaches long life anti-rust agents comprising thermoplastic resins containing cyclodextrin inclusion compounds of vaporisable anti-rust agents. No benefit from a time release perspective is seen from the encapsulation of phenolic antioxidants as taught by the ""169 French publication because any phenolic antioxidants which are employed are immediately consumed as the result of an activating event.
Although this technology is well known for use in connection with a variety of applications, none of the applications relate to its use in connection with personal care absorbent articles. Such applications may include the time release of compounds for odor control, for fluid distribution control on an as needed basis, for application of medicaments over time, and generally for controlled delivery of additives used in such products and for photostabilization of polymers employed in materials such as car seat covers.
It is one object of this invention to provide a method for controlling the delivery of additives used in personal care absorbent articles, including, but not limited to, disposable diapers, training pants, incontinence garments, feminine hygiene products, health care products and industrial fabrics.
It is another object of this invention to control the benefit derived from additives to personal care absorbent articles, for example, to extend the period over which the benefit may derived or to render the benefit upon the occurrence of an activation event.
These and other objects of this invention are addressed by a nonwoven material comprising at least one time release additive, which nonwoven material is suitable for use in personal care absorbent articles including disposable diapers, training pants, incontinence garments, feminine hygiene products, health care products and industrial fabrics. Such personal care absorbent articles typically comprise a cover sheet and a back sheet, at least one of said cover sheet and said back sheet comprising a time release additive. In accordance with one embodiment of this invention, an absorbent core is disposed between said cover sheet and said back sheet, in which case the time release additive may be disposed within the absorbent core. Time release of additives in accordance with one embodiment of this invention is achieved by encapsulating the additive in a controlled release material selected from the group consisting of zeolites, cyclodextrin, cage molecules, natural and synthetic minerals and combinations thereof.
In accordance with one preferred embodiment of this invention, at least one of the cover sheet, the back sheet and the absorbent core comprises a film, a nonwoven material or a laminate comprising at least one polymeric material. The encapsulated additive may be disposed on the surface of the cover sheet, the back sheet and/or the absorbent core, and/or in the interior of the cover sheet, the back sheet and/or the absorbent core, and/or incorporated into the polymer used to produce the cover sheet, the back sheet and/or the absorbent core.